Telephone



l. LANGMUIR.

TELEPHONE. APPLlCATION FILED APFLZI, 19H- Patnted Jun 7,4921.

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Inventor: IrvWmui F H is JIttorney To all whom itmwy concrn. Be it knownthat I, Invms LANGMUJR, a

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- citizen of the United States, residing at Schenectady, in the countyof Schenectady,

Stateof New York, have invented certain new and useful Improvements inTelephones, of which the following is a speci- Loud speaking telephonereceivers have been suggested having a diaphragm of relatively largesurface area to increase the vollune of the soiind without introducingthe large surface if constituted of a continuous sheet and acted upon asproposed by a single reproducer element will vibrate in section s'out ofsynchronism with each other, therebyloweringthe eiiiciency of the soundreproduction.

In accordance with my invention, I have provided a novel diaphragm oflarge area, preferably of a diameter of at least about two feet which isabout the length of sound waves of the most predominant frequency inspeech. It is desirable, however, to have the size of the reproducergreater than two feet diameter. .The large area diaphragm which is.us'eful either as a receiver or trans-' mitter, consistseith'e'r of anumber of aggregated small diaphragms each with its individual actuatingelement, that is reproducer or transmitter element, or of a single"Large size diaphragm acted upon by a numer of reproducer or transmitterelements.- Such a diaphragm vibrates as a unit. -When used as areproducer the sound produced thereby is free fi'om distortion. Theadvantages of such a diaphragm as a transmitter Wlll be pointed outhereinafter.

In the accompanying drawings, Figure 1 is a diagrammatic sectional viewof an electrostatic telephone unit; Fig. 2 is a plan view. of anarrangement of electrostatic units aggregated to form a reproducer oflarge surface; Fig; 3 is a diagram of electribal connections for acomposite electrostatic. receiver; Fig. 4 is 'a' diagram of electricalconnections for a composite electromagnetic receiver; 5 is a sectionalview of one form of a composite electromagnetic telephone and Fig. 6 isa plan view of part of a composite electromagnetic telephone; i" 7 Eachelectrostefiis fieteiver, Shawn in a horn. I.

Specification of Letters Patent. Pafignfiedi J7 7'31, 19213,,Application filed. April 21, 1917. Serial No. 163,730.

Fig. '1, consists alternately of sheets 0r an.-

ductive and sheets of dielectric material for example, of foil sheets 1alternating trostatic diaphragm need not he a plane but may be curved ifdesired a These electrostatic diaphragms may beef large area, at leastof the same order of magnitude as the sound waves, or. as shown Q inFig.2 a number of units are placed Side by side and electricallyconnected to form; a resultant large diaphragm. For the sake of'clearness only a-few electrical connections are shown in Fig. 2, theelectrical parallel connection being 1m:

cated in Fig. 3. dicated'in this figure a conductor 5 is connectedrespectively. to one set of condenser telephone. sheets and a conductor6 to the condenser sheets of opposite polarity. A telephone current maybe delivered tothese conductors by a suitable telephonepreferablyconnect,

ma indied in circuit; with an amplifier. For example, I have shdwn amicrophone transmitter 7, anda battery 8, connected to the primarywindingof a transformer 9.' The secondary circuit of this transformer isconnected by conductors 10, 11 respectively to the grid 12 and thefilament cathode 13 of a thermionic relay pliotron described in theProc. of the Institute' of Radio Engineers for September 1915. Inclosedthe evacuated en- ,velop 14 of the relayis also a plate or anode .15,the terminals of the cathode 13, and the anode 15 are connectedrespectively by the conductors 16, 17 to the of a trans-V former 18.Included in circuit with the cathode and anode is a battery 32, thenegative terminal being connected to the cathode.

The secondary of the transformer 18 is coir" nected to the conductors 5,6 in. series with a battery 19, which maintains a definite po tentialon'the condensers. r

In Fig. 4.: I have sham a single large area magnetic telephone 2d actedupon by a plurality of magnetic reproducer such for example, as theelements 21, each of which is wound upon a magnetic core 22 and'iselectriefiy con- 7 nected to the conductors "The conduetors 23, 2e are.connected asuitable transmitter system, transmitter system similar tothat shown in Fig. 3 being shown as symbolic.

Instead of a single large size diaphragm a number of small magnetlcdiaphragms, each associated with an individual winding, may be placedside by side to form a transmitter or receiver having a diameter atleast as great as the length of the sound waves of the predominantfrequency of speech or other sound to be transmitted electrically.

As shown in Fig. 5, the magnetic cores 25 orchestra.

are mechanically supported by a base 26 consisting of wood or othersuitable insulating material. As shown, the ends of the cores 25 whichmay be reduced in section, are inserted into holes made in the base 26,and provided with windings 27. Ad'acent the ends of the magnet cores arefixe magnetic diaphragms 28, held in position by a cover 29 fastened byscrews 30. The windings 27 may be connected inparallel as shown in Fig.4, to the conductors 23, 24 at the binding screws 81. Theindividualdiaphragms 28 vibrating in unison produce substantially theeffect of a diaphragm of the combined area of the combined diaphragms.

When used as a reproducer or receiver the sound volume is thus greatlyaugmented. When a telephone embodying my invention is used astransmitters sound may be gathered from a given direction with a minimumof disturbing sounds being included coming from other directions, andwhen it is used as a reproducer a beam of sound is produced and orientedat will. It is also possible to more perfectly gather sounds coming froma large number of units as for example, an When used as a transmitterthe conductors 5, 6 of Fig. 3 and the conductors 23, 24 of Fig. 4 aredisconnected from the relay transformers and connected to the usualtelephone transmission system.

What I claim as new and desire to secure 1 by Letters Patent of theUnited States, is:

a plurality of telephone elements arranged to act on individual sectionsof said diaphragm and means for energizing said elements in unison witha telephonic current.

2. A telephone comprising a plurality of face having a diameter of theorder of magnitude of at least about two feet, and means vibrating saidmembers in unison in responseto a telephonic current.

3. A. telephone comprising a diaphragm having a diameter at least asgreat as the length of a predominant wave of sound to be transmitted, aplurality of telephone actuating elements in operative relation to saiddiaphragm, each of said elements acting upon a diaphragm sectionproportioned to vibrate as a unit, and electrical conductors connectingsaid elements in parallel.

4. A telephone having a plurality of diaphragm sections associatedtogether to constitute a compositediaphragm havinga diameter at least asgreat as the length of a predominant wave of sound to be reproduced. aplurality of electrostatic telephone reproducer elements, each of whichis in operative. relation with one of said diaphragm sections and meansfor operating said reproducer elements to vibrate said compositediaphragm as a unit.

5.- A telephonic device comprising the combination of a plurality ofdiaphragms adapted to individually vibrate as units, said diaphragmsbeing combined to constitute a vibrating surface having a diameter of atleast about two feet and a plurality of telephone elements connectedelectrically in parallel and arranged to cooperate individually withsaid diaphragms.

'6. A telephonic device comprising the combination of a plurality ofelectrostatic telee phones containing vibrating dielectric diaphragmsand adapted to individually vibrate as units, said telephones beingcombined to constitute a composite diaphragm having a diameter of atleast about two feet, an electrical circuit connecting the electrodes ofsaid telephones electrically in parallel and an electrical amplifieroperatively connected to said circuit.

In witness whereof, I have hereunto set Witnesses:

MAX Wnrsnnon, WALTER A. ROMER.

